SNiP 2.05.06-85

SNiP in English 2.05.06-85*

СНиП на английском языке 2.05.06-85*

5.2. Embedding of pipelines transporting hot products at positive temperature difference in tube metal shall be additionally confirmed by calculation of longitudinal stability of pipelines subjected to compressive temperature stress in accordance with the provisions of Part 8.

5.3. Bottom width of trench shall be no less than:

D + 300 mm — for pipeline diameter of up to 700 mm;

1,5 D— for pipelines diameter 700 mm or more. In case of pipeline diameter 1,200 and 1,400 mm and trench acclivity over 1 : 0,5 the bottom width of trench can be decreased to D+500 mm, where Dis rate diameter of pipeline.

In case of pipeline ballasting, trench width shall ensure that the distance between the ballast and trench wall is no less than 0.2 m.

5.4. In sections of route with rough terrain of water-logged ground pipelines can be laid in special earth mounds, each layer of such mounds is carefully compacted and surface soil subjected to densification. At waterway cross-points the mound body shall have water vents.

5.5. In case of mutual crossing of pipelines the distance between them shall be at least 350 mm and intersection angle shall be no less than 60°.

Pipeline intersection with other pipelines or other utility lines (water supply, sewerage, cables, etc.) shall be designed in accordance with requirements of SNiP ??-89-80.

5.6. Pipelines diameter 1,000 mm or more shall require advance planning of the route. Planning of construction strip in the area of moving dunes shall involve dune cutting to the to the level of inter-dune bed without disturbing naturally compacted ground. After pipelined is laid and filled up the layer of dune sands on top of it and at the distance of at least 10 m from pipeline centerline on both sides shall be stabilized with couplers (neurosin, by-products of cracking bitumen, etc.). After pipelined is laid and filled up the layer of dune sands on top of it and at the distance of at least 10 m from pipeline centerline on both sides shall be stabilized with couplers (neurosin, by-products of cracking bitumen, etc.).

Design of 700 mm or larger diameter pipelines shall indicate both ground elevation and projected pipeline elevations on the longitudinal profile.

5.7. When pipelines is laid and filled-in in rock, gravel or crushed stone soils, at least 10 cm-thick layer of soft soil shall be added. In such case insulation coating shall be protected from damage by covering pipeline with a 20 cm-thick layer of soft soil and application of special agents to ensure protection of insulation coating in the process of filling.

5.8. Design of underground pipelines in areas where type II of soil settlement occurs shall take into account the requirements stated in SNiP  2.02.01-83.

Design of pipelines for type ? soil settlement conditions shall proceed in the manner applied to non-settling soils.

Note: The type of soil settlement and the amount of likely soil settlement shall be established in accordance with the provisions of SNiP 2.02.01-83.

5.9. In case pipeline is laid along terrain inclination of over 20%, anti-erosion screens and barricades made of natural soils (for instance, clay) or man-made materials shall be applied.

5.10. Design of pipelines laid on hills shall stipulate intercepting channels to divert surface water from the pipeline.

5.11. In case it is impossible to avoid settlement of pipeline bed, the pipeline durability and stability calculations shall take account of additional curve stress caused by bed settlement.

5.12. In case active ravines or valleys occur in the vicinity of pipeline route, which might affect safety of pipeline operation, solidification measures shall be stipulated.

5.13. Fixed benchmarks at intervals not exceeding 5 km shall be installed on pipeline route.

Pipeline laying in mountainous conditions

5.14. In mountainous conditions and rough terrain areas pipelines should be laid in river valleys outside flood zone or along watershed sectors, avoiding unstable of steep slopes as well as cloudburst flood areas.

5.15. In landslide zones with low thickness of sliding soil layer underground laying shall stipulate burying pipeline below the sliding plane.

Extended landslide areas shall be bypassed above the sliding slope.

5.16.* At crossings of cloudburst flood zones, as rule, above-ground laying should be applied.

In case of underground laying across cloudburst flood or slope wash pipeline laying shall be executed 0.5 m (from the tube top) lower than the likely bed erosion at 5% probability. In case of crossing slope wash pipeline laying shall be made in curve bypassing the outer edge of the slope wash at the depth, which is lower than the likely erosion within erratic river beds.

Selection of pipeline laying type and design decisions regarding pipeline protection in case of crossing cloudburst flood zones shall ensure reliability of pipelines and performance characteristics.